Standards and Design Guidelines on Artificial Lighting for Indoor Farming

Light is one of the key requirements in agriculture. It influences the nutritional composition and shape of a plant. The right combination between light intensity, its spectral composition and exposure time will affect the overall quality of the plant.

Plants are mostly cultivated under natural sunlight, but electrical lamps and luminaires are being used as well, either as a substitute or as a standalone solution. The development of electric lighting for agriculture and horticulture has closely followed that for human lighting. Artificial light has gained in popularity in recent years due to greater control and customizability to meet a plant’s needs. In particular the LED technology added additional complexity due to its potential to easily provide a high degree of wavelength combinations. The conditions under which plants are grown differ from those for general lighting. If required the climate can typically range from normal to tropical. Some of these environmental conditions can proof to be challenging for lighting systems. This includes damp or wet areas, setups with high temperatures and rooms with a controlled environment. Under damp and wet conditions the light fixtures are exposed to moisture or water. Especially when humidity is high or frequently changing then this kind of environment can lead to moisture and water entering the light fixture which could damage its lighting components. Some applications, e.g. rotary hydroponic farming, can bring the casing or the electronics in contact with water when not designed properly which is a security risk. Another underestimated issue of light fixtures is the ingress of dust and particles. Dust or in some cases insects can diminish the light output when entering and accumulating in the fixtures interior. Fumes from e.g. fertilizers can also impact the enclosures structural integrity and the lenses transparency especially when they made of plastic.

Thermal management is a common issue with LED technology. LED luminaires are in general in need of cooling, and deposition of dust on its cooling components could lead to overheating of the electronics diminishing overall efficiency and even its destruction. The cooling of the LEDs and its electronics is of particular importance when being operated under high temperatures. High ambient temperatures or cycling temperatures can stress the casing and electrical contacts of the luminaires which can pose a safety risk.

In rooms for high precision farming where temperature, humidity and C02 are tightly controlled air-handling recessed fixtures may be required that provide either air supply, air return or both.
Light solutions should be tested for certain parameters to ensure optimal performance and guarantee over all safety of the product. Testing horticultural lightings according to existing standards for harsh environments such as water ingress and operation under various temperatures would improve the overall performance of horticultural lightings.

Light planning is for plants as important as for human. But instead of concentrating on the visibility of a scenery, light for plants is aiming at the quality and the wellbeing of the plants. The greater flexibility and customization in light design has resulted in a higher variety of light solutions of which not all will have a positive impact on plant growth. Available standards in the field of horticulture promote the usage of the correct terminology and a unified approach for recording necessary parameters such as humidity, light level and light distribution. The data gained from these measurements will enable light planners to enhance the quality of the illumination in a similar fashion as in general lighting.